lrSib {relSim}

Likelihood Ratio / Kinship Index for full-siblings

Description

Calculates Likelihood Ratio comparing the probability of two profiles if they are indeed full-sibs compared to unrelated. This is sometimes called the kinship index (KI) for full-sibs.

Usage

lrSib(sib1, sib2, Freqs = NULL, nLoci = length(sib1)/2, f = NULL, n = NULL)

Arguments

sib1

A matrix consisting of 2 columns and nLoci rows. Each entry in the matrix is the (coded) allele held by the individual. This represents the alleged sibling. The relationship is reflexive so it does not matter which profile is labelled sib1 and sib2.

sib2

See sib1

Freqs

A list containing two lists labelled loci and freqs. The second list is a list of vectors containing the allele frequencies of each allele at each locus in the multiplex. This argument or both f and n must be specified

nLoci

The number of loci in the profiles

f

A concatenated vector of allele frequencies. Specifying this speeds up computation enormously

n

A vector of length nLoci giving the number of alleles at each locus. Specifying this in advance enormously speeds up computation

Value

A value between 0 and infinity representing support (or lack of support if the value is less than 1) for the hypothesis that the two profiles are full-siblings. There is no mutation built into this calculation.

Author(s)

James M. Curran

References

Buckleton, J, Triggs, C.M., and Walsh, S.J. (2005)Forensic DNA Evidence Interpretation, CRC Press., Boca Raton, FL. p.411

See Also

lrSibDebug, lrPC, IBS

Examples

data(fbiCaucs)
P1 = randomProfile(fbiCaucs)
S1 = randomSib(P1, fbiCaucs)
P2 = randomProfile(fbiCaucs)
lrSib(P1, S1, fbiCaucs)
lrSib(P1, P2, fbiCaucs)